Benefits of a Circular Layout

Circos uses a circular composition mitigate the fact that data which represent connections between objects or between positions are very difficult to organize when the underlying layout is linear (or a graph, which can quickly become a hairball). In many cases, a linear layout makes impossible keeping the relationship lines from crossing other structures, deteriorates the effectiveness of the graphic.

▴ From sketch to figure. The image shows short- and long-range interactions, and genome variation on human chromosome 21.

▴ From sketch to figure. The image shows short- and long-range interactions, and genome variation on human chromosome 21.

In addition to its strength in depicting links, the circular form itself has a number of useful properties which are not shared by a rectilinear layout.

• For a given square area on a page (e.g. square of side z), the circular layout can support a larger data domain (i.e. 2πz ~ 6z) than the square (i.e. z). More data can be shown within a given space on a page (or within narrower field of vision).
• Within the circle, the resolution varies linearly, increasing with radial position. This makes the center of the circle ideal for compactly displaying summary statistics or indicating points of interest (i.e. low resolution data) which the reader can then follow outward to explore the data in greater detail (i.e. high resolution data).
• The circular form encourages eye movementto proceed along curved lines, rather than in a zig-zag fasion in a square or rectangular figure.

I've applied circular compositing to represent database structure with Schemaball.

▴ From sketch to figure. The image shows short- and long-range interactions, and genome variation on human chromosome 21.